Linear accelerators and X-ray tubes are widely used in fields including medicine, non-destructive testing (NDT), security inspection, etc. Both a linear accelerator and an X-ray tube may employ a bremsstrahlung converter (BCs) to generate X-ray radiation from incident charged particles. As the charged particles are slowed inside the BC, X-ray photons may be generated. A BC may be referred to as an X-ray target or simply target. A target, often packaged in a target assembly, may be made of a material having a high atomic weight and a high melting point, such as tungsten (W), rhenium, tantalum (Z), etc. During the bremsstrahlung process, incident charged particles may deposit such a significant amount of their kinetic energy in the target that the target material and the target assembly may become hot or even melt. The hot target material may become oxidized if it is exposed to air, and the produced volatile oxides may vaporize at the working temperature of the target. In a conventional linear accelerator or X-ray tube, the target may reside within a vacuum chamber or a chamber filled with a non-reactive gas, or be directly exposed to the ambient air. A target assembly with the target residing in a vacuum or in a non-reactive gas atmosphere may be complicated to manufacture, while a target directly exposed to the ambient air may suffer from a reduced lifespan due to oxidation corrosion at its working temperature. Accordingly, there is a need for a target assembly that may provide an efficient protection and cooling for a target packaged therein and be convenient to manufacture.